For two weekends in August Oak Bluffs goes dancing. The beating of drums begins around 7:30 p.m., beckoning people to the corner of Grove and Narragansett avenues. Inside Union Chapel dancers sway and stretch and leap, warming up to the drumbeats.

Built on Stilts is the Vineyard’s homegrown dance festival and it takes root this summer from August 8 through the 11 and again from August 17 through the 20 at Union Chapel in Oak Bluffs. Choreographers from Martha’s Vineyard and visiting artists from off-Island join creative forces to bring the performances to life. The program is always free and changes each night. Each night begins with a drum circle starting at 7:30 p.m. The Dance program follows at 8 p.m.

Outside Union Chapel last Saturday evening people lingered on the stairs; little girls doing each other’s makeup and mothers making small talk, all the while keeping an eye on the green doors behind them. At 7:30 p.m. sharp, the doors of the chapel opened and the people streamed inside, running to the closest seat and marking their territory in preparation for this summer’s edition of Built on Stilts.

It all begins with the drum circle. At first it’s just a few folks sitting behind their drums, striking the beat ever so softly. But the scene is being set at Union Chapel in Oak Bluffs and quickly it begins to build as the audience streams in, no need for money or tickets, not on this night.

Red wine and cigarettes, dirty jokes and skinny dipping, late night sorties onto the streets of Oak Bluffs in outrageous costume — the manifestations of Abby Bender and Brent Alberghini’s 14-year relationship tend toward the risky and risque. But 12 years ago their offbeat ideas of friendship and community also nurtured something of an Island institution, the annual Built on Stilts community dance festival. The festival begins its week-long run this coming Friday.

Chaos rules at Stiltshop, where day camp-style rehearsals prepare youngsters to participate next to older and more experienced dancers in Built on Stilts, the Island’s annual homegrown community dance festival. Call it Built on Stilts with a shorter attention span.

Built on Stilts, the annual dance festival held at the Union Chapel in Oak Bluffs, opened last night to begin its eight day run with a bit of drumming, belly dancing and a group of five-year-olds taking the stage fresh from their yearlong “Stiltshop” choreography class. What’s on the schedule for tonight is anyone’s guess, though, as the show never repeats itself.